A ClearSCADA server contains the database and the driver(s) that are used to communicate with the outstations and other devices on your system. A ClearSCADA system can have more than one server, but only one server can be ‘main’ (run the drivers and communicate with the clients and hardware) at any one time.
Each driver contains additional support to enable the ClearSCADA server to communicate with other devices (such as PLCs or outstations) using one particular communications protocol. For example, the Simple Modbus driver uses the Modbus protocol to communicate with Modbus PLCs. Each driver scans the devices that are using that particular protocol and for which valid configuration exists in the ClearSCADA database. For more information, see the Driver Reference Suite.
When you use a ClearSCADA client to perform an action on plant, the action is sent from your client to the ClearSCADA server. The driver sends the action to the relevant device, and the device processes the action to control the plant.
The ClearSCADA server requests data from the outstations and other devices at regular user configured intervals. Data can also be requested manually at any time. The data the ClearSCADA server receives is stored in the database, which contains database points that correspond to the plant.
Further Information
The types of driver that ClearSCADA supports: see Types of Driver
Master-slave communications: see Master-Slave Communications